The Adolescent AIDS Program (AAP) at Montefiore Medical Center of the Albert Einstein College of Medicine in the Bronx, New York is applying to be an Adolescent Medicine Trials Unit (AMTU) in the Adolescent Medicine Trials Network for HIV/AIDS Interventions (ATN). The AAP has more than a decade of experience and leadership in providing the highest quality clinical care and research with HIV-positive and at-risk youth. The AAP is located in the Bronx, New York, a locale with very high rate of HIV and other sexually transmitted infections. The AAP has a demonstrated ability yo maintain a cohort of more than one hundred HIV-positive youth (more than 225 cumulatively), the majority of whom have acquired HIV infection through sexual behaviors, and mostly youth of color, as well as a cohort of more than four hundred at-risk sexually experienced youth. The AAP has engaged more than one hundred HIV-positive youth and more than one hundred HIV-positive youth and more than 1000-HIV negative youth in clinical research in more than ten multi-site studies, including course of HIV disease (REACH, NIH), clinical trials (ACTG, NIH), behavioral interventions (TLC, CLEAR, NIH), risk behavior analyses (CDC) and others. The AAP plans to be an active and effective AMTU based on the following three components: 1) an experienced Principal Investigator and three Study Coordinators who have built and maintained the second most active site in the Adolescent Medicine HIV/AIDS Research Network, in addition to a long history as a Pediatric AIDS Clinical Trial Unit and experience in other multi-site studies; 20 a well-coordinated comprehensive care team started by medical and mental health practitioners experienced in HIV care and adolescent health; and 3) an innovative community outreach program, including the successful social marketing campaign "HIV. Live with it. Get Tested.", with strong relationships with community agencies serving at risk adolescents. Thus, the AAP will offer important scientific and operational contributions in meeting the research agenda posed in the Request for Applications by the National Institutes of Health.